Wireless inventory management system

ABSTRACT

An inventory management system for wirelessly taking inventories of medical trays comprises an easily assemblable and disassemblable enclosure comprising interconnected electrically conductive walls to form a Faraday cage. The interior space defined by the walls is large enough to accept the trays. RFID readers are placed within the enclosure directed at the tray to excite and read the RFID tags disposed on the medical articles within the tray. The walls of the enclosure are flexible and one of the walls is rolled up and down to act as an opening to the interior space. A host computer stores the inventory of the tray and compares it against a previous inventory existence for resupply purposes. The host computer also detects expired and recalled medical articles in the tray. If a recalled article is detected, the host computer determines if a substitute article exists.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/413,278, filed Jan. 23, 2017, now U.S. Pat. No. 10,360,350, which isa continuation of U.S. application Ser. No. 14/853,944, filed Sep. 14,2015, now U.S. Pat. No. 9,552,568, which is a continuation of U.S.application Ser. No. 14/210,287, filed Mar. 13, 2014, now U.S. Pat. No.9,135,482, which is a continuation-in-part of U.S. application Ser. No.13/776,613 filed Feb. 25, 2013, now U.S. Pat. No. 8,686,859, and whichclaims the benefit of U.S. Provisional Application No. 61/780,698, filedMar. 13, 2013, and which is a continuation of U.S. application Ser. No.12/631,861, filed Dec. 7, 2009, now U.S. Pat. No. 8,384,545, all ofwhich are incorporated herein by reference.

BACKGROUND

The invention relates generally to the field of tracking medicalarticles in a healthcare setting, and more particularly, to a system andmethod for managing the inventory of a mobile medical dispensing cart.

There are a number of ways of identifying and tracking articlesincluding visually, optically (bar coding, for example), magnetically,electro-magnetically (RFID), weighing, and others. Where an automaticsystem for tracking is desired, RFID is a candidate since identificationdata may be obtained wirelessly. RFID tags have decreased in cost, whichhas made them even more attractive for such an application.

Radio-frequency identification (“RFID”) is the use of electromagneticenergy (“EM energy”) to stimulate a responsive device (known as an RFID“tag” or transponder) to identify itself and in some cases, provideadditionally stored data. RFID tags typically include a semiconductordevice having a memory, circuitry, and one or more conductive tracesthat form an antenna. Typically, RFID tags act as transponders,providing information stored in the semiconductor device memory inresponse to an RF interrogation signal received from a reader, alsoreferred to as an interrogator. Some RFID tags include securitymeasures, such as passwords and/or encryption. Many RFID tags alsopermit information to be written or stored in the semiconductor memoryvia an RF signal.

RFID tags may be incorporated into or attached to articles to betracked. In some cases, the tag may be attached to the outside of anarticle with adhesive, tape, or other means and in other cases, the tagmay be inserted within the article, such as being included in thepackaging, located within the container of the article, or sewn into agarment. The RFID tags are manufactured with a unique identificationnumber which is typically a simple serial number of a few bytes with acheck digit attached. This identification number is incorporated intothe tag during manufacture. The user cannot alter thisserial/identification number and manufacturers guarantee that eachserial number is used only once. This configuration represents the lowcost end of the technology in that the RFID tag is read-only and itresponds to an interrogation signal only with its identification number.Typically, the tag continuously responds with its identification number.Data transmission to the tag is not possible. These tags are very lowcost and are produced in enormous quantities.

Such read-only RFID tags typically are permanently attached to anarticle to be tracked and, once attached, the serial number of the tagis associated with its host article in a computer data base. Forexample, a particular type of medicine may be contained in hundreds orthousands of small vials. Upon manufacture, or receipt of the vials at ahealth care institution, an RFID tag is attached to each vial. Each vialwith its permanently attached RFID tag will be checked into the database of the health care institution upon receipt. The RFIDidentification number may be associated in the data base with the typeof medicine, size of the dose in the vial, and perhaps other informationsuch as the expiration date of the medicine. Thereafter, when the RFIDtag of a vial is interrogated and its identification number read, thedata base of the health care institution can match that identificationnumber with its stored data about the vial. The contents of the vial canthen be determined as well as any other characteristics that have beenstored in the data base. This system requires that the institutionmaintain a comprehensive data base regarding the articles in inventoryrather than incorporating such data into an RFID tag.

An object of the tag is to associate it with an article throughout thearticle's life in a particular facility, such as a manufacturingfacility, a transport vehicle, a health care facility, a storage area,or other, so that the article may be located, identified, and tracked,as it is moved. For example, knowing where certain medical articlesreside at all times in a health care facility can greatly facilitatelocating needed medical supplies when emergencies arise. Similarly,tracking the articles through the facility can assist in generating moreefficient dispensing and inventory control systems as well as improvingwork flow in a facility. Additionally, expiration dates can be monitoredand those articles that are older and about to expire can be moved tothe front of the line for immediate dispensing. This results in betterinventory control and lowered costs.

Other RFID tags are writable and information about the article to whichthe RFID tag is attached can be programmed into the individual tag.While this can provide a distinct advantage when a facility's computerservers are unavailable, such tags cost more, depending on the size ofthe memory in the tag. Programming each one of the tags with informationcontained in the article to which they are attached involves furtherexpense.

RFID tags may be applied to containers or articles to be tracked by themanufacturer, the receiving party, or others. In some cases where amanufacturer applies the tags to the product, the manufacturer will alsosupply a respective data base file that links the identification numberof each of the tags to the contents of each respective article. Thatmanufacturer supplied data base can be distributed to the customer inthe form of a file that may easily be imported into the customer'soverall data base thereby saving the customer from the expense ofcreating the data base.

Many RFID tags used today are passive in that they do not have a batteryor other autonomous power supply and instead, must rely on theinterrogating energy provided by an RFID reader to provide power toactivate the tag. Passive RFID tags require an electromagnetic field ofenergy of a certain frequency range and certain minimum intensity inorder to achieve activation of the tag and transmission of its storeddata. Another choice is an active RFID tag; however, such tags requirean accompanying battery to provide power to activate the tag, thusincreasing the expense of the tag and making them undesirable for use ina large number of applications.

Depending on the requirements of the RFID tag application, such as thephysical size of the articles to be identified, their location, and theability to reach them easily, tags may need to be read from a shortdistance or a long distance by an RFID reader. Such distances may varyfrom a few centimeters to ten or more meters. Additionally, in the U.S.and in other countries, the frequency range within which such tags arepermitted to operate is limited. As an example, lower frequency bands,such as 125 KHz and 13.56 MHz, may be used for RFID tags in someapplications. At this frequency range, the electromagnetic energy isless affected by liquids and other dielectric materials, but suffersfrom the limitation of a short interrogating distance. At higherfrequency bands where RFID use is permitted, such as 915 MHz and 2.4GHz, the RFID tags can be interrogated at longer distances, but theyde-tune more rapidly as the material to which the tag is attachedvaries. It has also been found that at these higher frequencies, closelyspaced RFID tags will de-tune each other as the spacing between tags isdecreased.

There are a number of common situations where the RFID tags may belocated inside enclosures. Some of these enclosures may have entirely orpartially metal or metallized surfaces. Examples of enclosures includemetal enclosures (e.g., shipping containers), partial metal enclosures(e.g., vehicles such as airplanes, buses, trains, and ships that have ahousing made from a combination of metal and other materials), andnon-metal enclosures (e.g., warehouses and buildings made of wood).Examples of objects with RFID tags that may be located in theseenclosures include loose articles, packaged articles, parcels insidewarehouses, inventory articles inside buildings, various goods insideretail stores, and various portable articles (e.g., passengeridentification cards and tickets, baggage, cargo, individual life-savingequipment such as life jackets and masks) inside vehicles, etc.

The read range (i.e., the range of the interrogation and/or responsesignals) of RFID tags is limited. For example, some types of passiveRFID tags have a maximum range of about twelve meters, which may beattained only in ideal free space conditions with favorable antennaorientation. In a real situation, the observed tag range is often sixmeters or less. Therefore, some of the enclosures described above mayhave dimensions that far exceed the read range of an individual RFIDtag. Unless the RFID reader can be placed in close proximity to a targetRFID tag in such an enclosure, the tag will not be activated and read.Additionally, metal surfaces of the enclosures present a seriousobstacle for the RF signals that need to be exchanged between RFIDreaders and RFID tags, making RFID tags located behind those metalsurfaces difficult or impossible to detect.

In addition to the above, the detection range of the RFID systems istypically limited by signal strength to short ranges, frequently lessthan about thirty centimeters for 13.56 MHz systems. Therefore, portablereader units may need to be moved past a group of tagged items in orderto detect all the tagged items, particularly where the tagged items arestored in a space significantly greater than the detection range of astationary or fixed single reader antenna. Alternately, a large readerantenna with sufficient power and range to detect a larger number oftagged items may be used. However, such an antenna may be unwieldy andmay increase the range of the radiated power beyond allowable limits.Furthermore, these reader antennae are often located in stores or otherlocations where space is at a premium and it is expensive andinconvenient to use such large reader antennae. In another possiblesolution, multiple small antennae may be used but such a configurationmay be awkward to set up when space is at a premium and when wiring ispreferred or required to be hidden.

In the case of medical supplies and devices, it is desirable to developaccurate tracking, inventory control systems, and dispensing systems sothat RFID tagged devices and articles may be located quickly should theneed arise, and may be identified for other purposes, such as expirationdates. In the case of medical supply or dispensing cabinets used in ahealth care facility, a large number of medical devices and articles arelocated closely together, such as in a plurality of drawers. Cabinetssuch as these are typically made of metal, which can make the use of anexternal RFID system for identification of the stored articlesdifficult. In some cases, such cabinets are locked due to the presenceof narcotics or other medical articles or apparatus within them that aresubject to a high theft rate. Thus, manual identification of the cabinetcontents is difficult due to the need to control access.

Providing an internal RFID system in such a cabinet can pose challenges.Where internal articles can have random placement within the cabinet,the RFID system must be such that there are no “dead zones” that theRFID system is unable to reach. In general, dead zones are areas inwhich the level of coupling between an RFID reader antenna and an RFIDtag is not adequate for the system to perform a successful read of thetag. The existence of such dead zones may be caused by orientations inwhich the tag and the reader antennae are in orthogonal planes. Thus,articles placed in dead zones may not be detected thereby resulting ininaccurate tracking of tagged articles.

Often in the medical field, there is a need to read a large number oftags attached to articles in such an enclosure, and as mentioned above,such enclosures have limited access due to security reasons. Thephysical dimension of the enclosure may need to vary to accommodate alarge number of articles or articles of different sizes and shapes. Inorder to obtain an accurate identification and count of suchclosely-located medical articles or devices, a robust electromagneticenergy field must be provided at the appropriate frequency within theenclosure to surround all such stored articles and devices to be surethat their tags are all are activated and read. Such medical devices mayhave the RFID tags attached to the outside of their containers and maybe stored in various orientations with the RFID tag (and associatedantenna) pointed upwards, sideways, downward, or at some other angle ina random pattern.

Generating such a robust EM energy field is not an easy task. Where theenclosure has a size that is resonant at the frequency of operation, itcan be easier to generate a robust EM field since a resonant standingwave may be generated within the enclosure. However, in the RFID fieldthe usable frequencies of operation are strictly controlled and arelimited. It has been found that enclosures are desired for the storageof certain articles that do not have a resonant frequency that matchesone of the allowed RFID frequencies. Thus, a robust EM field must beestablished in another way.

Additionally, where EM energy is introduced to such an enclosure forreading the RFID tags within, efficient energy transfer is ofimportance. Under static conditions, the input or injection of EM energyinto an enclosure can be maximized with a simple impedance matchingcircuit positioned between the conductor delivering the energy and theenclosure. As is well known to those of skill in the art, such impedancematching circuits or devices maximize the power transfer to theenclosure while minimizing the reflections of power from the enclosure.Where the enclosure impedance changes due to the introduction or removalof articles to or from the enclosure, a static impedance matchingcircuit may not provide optimum energy transfer into the enclosure. Ifthe energy transfer and resulting RF field intensity within theenclosure were to fall below a threshold level, some or many of the tagson articles within the enclosure would not be activated to identifythemselves, leaving an ineffective inventory system.

It is a goal of many health care facilities to keep the use of EM energyto a minimum, or at least contained. The use of high-power readers tolocate and extract data from RFID tags is generally undesirable inhealth care facilities, although it may be acceptable in warehouses thatare sparsely populated with workers, or in aircraft cargo holds.Radiating a broad beam of EM energy at a large area, where that EMenergy may stray into adjacent, more sensitive areas, is undesirable.Efficiency in operating a reader to obtain the needed identificationinformation from tags is an objective. In many cases where RFID tags areread, hand-held readers are used. Such readers transmit a relativelywide beam of energy to reach all RFID tags in a particular location.While the end result of activating each tag and reading it may beaccomplished, the transmission of the energy is not controlled except bythe aim of the user. Additionally, this is a manual system that willrequire the services of one or more individuals, which can also beundesirable in facilities where staff is limited.

In a healthcare environment, there are many storage systems for medicalarticles that are used for different purposes and different patients.Some are open access storage systems. In most of these cases, andespecially for emergency storage systems, they must be restocked uponuse on a regular basis so that necessary medical articles will beavailable when needed. An example of such a medical article storagesystem is the medical cart used in rooms or in the hallways ofhealthcare facilities that are supplied to contain the medical articlesprescribed or otherwise needed by the patients residing in the area ofthe cart. FIG. 23 shows an example of a patient medication cart 300.Such carts usually, but not always, include wheels 302 so that they aremobile, and often have multiple drawers 304 in which various medicalarticles are stored for one or more patients being treated in thevicinity of the cart. Only two drawers are indicated by numeral 304 inFIG. 1 so that the clarity of the drawing is not obscured. It is meantthat the numeral 304 apply to all drawers. In this embodiment, eachdrawer has an external handle 306 provided for assisting a user inpulling the respective drawer 304 out of the cart frame 308.

Currently, hospital pharmacies dispense patient drugs and other medicalarticles into such a mobile cart to be delivered to the general floorwhere the patients are located. As mentioned, the cart has multipledrawer units that may be used for containing the medications of aplurality of patients. Each patient may have one or more drawers storinghis or her medications and other medical articles. The current systemallows open access by which a healthcare provider can take medicationsfrom a mobile or stationary cart for use with a patient other than thepatient for whom those medications have been prepared and accumulated inthe drawer of a cart. Multiple nurses have access to all the patientdrawers and often “shop” for medications from one patient's drawer andgive them to another patient. Errors can occur and often delays occur ifa patient's medications are not in the drawer when the patient's nurseintends to administer them.

An example of a drawer 320 in the cabinet of FIG. 23 is shown in FIG.24. The drawer has multiple pockets 322, in this case five. The pocketsmay have different sizes and shapes, and are used to store a patient'smedications or other medical articles. For example, drawer 320 of FIG.24 shows a vial of medication in one pocket, a blister pack of pills inanother pocket, and in the longer pocket, a pre-loaded syringe isstored. Many other medical articles may be stored in the drawer for thepatient, depending on the ailments causing the patient to be in thehealthcare facility. Should the pre-loaded syringe be taken from thepocket for use on a different patient instead of being left availablefor the patient for whom it was prepared, the latter patient may sufferuntil the pharmacy can prepare a new own.

Hence, those skilled in the art have recognized a need for a bettermeans of control over the dispensing of the medications and othermedical articles to patients from mobile or stationary carts thuspreventing errors as well as controlling improper drug retrieval.Another recognized need is to restrict the spread of electromagneticenergy in healthcare facilities. A further need has been recognized formanaging the inventory of such carts so that they may be resupplied on amore timely basis. Yet another need has been recognized for monitoringthe contents of such carts for expired and or recalled medical articles.Another need has been recognized for providing an accurate inventorydetection system using a wireless system with smaller enclosures. Theinvention fulfills these needs and others.

SUMMARY OF THE INVENTION

Briefly and generally there is provided a system and a method to managemedical articles stored in a mobile dispensing cart and to controlincorrect dispensing of those medical articles. There is provided amanagement system for managing inventory in a medical cart, theinventory comprising medical articles for dispensing to a patient, eachof the medical articles being identified by a wireless data carrierwhich is responsive to electromagnetic energy (EM) of a frequency f1 inresponse to which the wireless data carrier provides identificationdata, the management system comprising a metallic enclosure having aninternal reading area, the metallic enclosure located within the medicalcart and having electrically conductive walls that completely surroundthe internal reading area, the enclosure having a natural frequency ofresonance f2 which is different from the frequency f1 to which the datacarriers are responsive, the data carriers not being operationallyresponsive to frequency f2, a probe disposed at anelectrically-conductive wall of the metallic enclosure and configured toinject EM of a frequency f1 into the metallic enclosure, wherein theposition of the probe in relation to electrically-conductive walls ofthe metallic enclosure is selected so that reflected EM of frequency f1within the metallic enclosure is in phase at the probe position tothereby optimize power transfer at frequency f1 into the enclosure, anactive impedance matching circuit coupled to the probe and configured toactively match more closely impedance of the probe to impedance of themetallic enclosure at frequency f1, a storage area located within theinternal reading area of the metallic enclosure in the cart, the storagearea configured to contain medical articles with associated datacarriers identifying the medical articles, each data carrier beingresponsive to EM at frequency f1 but not operationally responsive tofrequency f2, the storage area having an access control device thatprevents access to the storage area when locked and allows access whenunlocked, a receiving antenna disposed within the metallic enclosure andconfigured to receive the identification data provided by the datacarriers in response to the injected EM, a processor, and a non-volatilememory in which is stored a data base that links a patient to medicalarticles stored for the patient in the storage area, and a data basethat links a health care provider to the patient, wherein the processoris programmed to unlock the storage area for access by a health careprovider linked to the patient, wherein the processor is programmed todetect and identify any medical article taken from the storage area,compare it to the patient data base, and if the medical article does notmatch the patient data base, provide an alarm.

In more detailed aspects, the memory comprises a data base of wirelessdata carrier identifications linked to medical article data in which oneof those medical article data is an expiration date of the respectivemedical article, wherein the processor is further programmed to receivethe data carrier identification data, access the data base of medicalarticle data corresponding to that data carrier identifications andcompare the expiration date of the identified medical articles to aselected date, and the processor being further programmed to provide anotice if the expiration date of a medical article falls on or beforethe selected date.

In yet other aspects, the memory includes a data base in which datapertaining to recalled articles are stored, and the processor furtherbeing programmed to compare the identification data of the medicalarticles in the storage container to the recalled article data base inthe memory, and if the comparison shows that a medical article isrecalled, to provide a notice of such recall status.

In method aspects according to the invention, there is provided a methodof managing inventory in a medical cart, the inventory comprisingmedical articles for dispensing to a patient, each of the medicalarticles being identified by a wireless data carrier which is responsiveto electromagnetic energy (EM) of a frequency f1 in response to whichthe wireless data carrier provides identification data, the managementmethod comprising preparing a patient data base that includes allmedical articles stored in the storage area for the patient, injectingelectromagnetic energy of a frequency f1 into a metallic enclosurelocated within the cart with a probe, the metallic enclosure havingelectrically conductive walls, wherein the position of the probe inrelation to the electrically conductive walls is selected so thatreflected EM of frequency f1 within the metallic enclosure is in phaseat the probe position to thereby optimize power transfer at frequency f1into the enclosure, the electrically conductive walls completelysurrounding an internal reading area of the enclosure, the enclosurehaving a natural frequency of resonance f2 which is different from thefrequency f1 and to which a data carrier that is responsive to frequencyf1 is not operationally responsive to frequency f2, wherein the storagearea is located within the metallic enclosure, actively matching theimpedance of a probe that is used to inject EM energy into the metallicenclosure more closely to impedance of the enclosure at frequency f1,controlling access to the storage area within the enclosure with alocking device, the storage area being inaccessible when the lockingdevice is locked and accessible when the locking device is unlocked,receiving a request from a health care provider to have access to thestorage area, comparing the patient to a patient data base to identify ahealth care provider assigned to the patient, unlocking the storage areaif the health care provider requesting access matches as being assignedto the patient, after the locking device is re-locked, detecting andidentifying any taken article from the storage area, comparing the takenarticle to the patient data base and if the taken article does not matchthe patient data base, providing an alarm.

In more detailed method aspects, the method further comprisesdetermining if a medical article in the storage area is expired throughlocating an article expiration date from a medical article data base,comparing that expiration date to a selected expiration date, andproviding a notice of expiration if the two dates match or if theexpiration date of the medical article preceded the selected date. Themethod yet further comprises comparing the data of a medical article inthe storage area to a recalled article data base on the memory, and ifthe comparison shows that the medical article is recalled, providing anindication of such recall status about the medical article.

The features and advantages of the invention will be more readilyunderstood from the following detailed description that should be readin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a drawer that may be positioned withina medical dispensing cabinet, showing the storage of a plurality ofmedical articles randomly positioned in the drawer, each of thosearticles having an integral RFID tag oriented randomly;

FIG. 2 is a perspective view of a medication dispensing cabinet havingfive drawers, one of which is similar to the schematic view of FIG. 1,the cabinet also having an integral computer for controlling access tothe cabinet and performing inventory tracking by periodically readingany RFID tags placed on articles stored within the cabinet, and forreporting the identified articles to a remote computer;

FIG. 3 is a block and flow diagram showing an embodiment in which anRFID reader transmits activating EM energy into a drawer containing RFIDtags with a single transmitting antenna, receives the data output fromthe activated RFID tags with a single receiving antenna, a computercontrolling the transmission of activating energy and receiving the datafrom the activated RFID tags for processing;

FIG. 4 is a block and flow diagram similar to FIG. 3 showing anembodiment in which an RFID reader transmits activating EM energy into adrawer containing RFID tags with two transmitting antennae, receives thedata output from the activated RFID tags with three receiving antennae,and as in FIG. 3, a computer controlling the transmission of activatingenergy and receiving the data from the activated RFID tags forprocessing;

FIG. 5 shows an enclosure with a single probe and a connector, the probebeing configured to inject EM energy into the enclosure and excite a TEmode;

FIG. 6 shows an enclosure with a single probe and a connector, the probebeing configured to inject EM energy into the enclosure and excite a TMmode;

FIG. 7 shows a plot of coupled power in an enclosure as a function offrequency for a resonant enclosure where F_(n) is the natural resonancefrequency of the enclosure;

FIG. 8 shows a plot of coupled power (ordinate axis) in an enclosure asa function of frequency (abscissa axis), where f_(f) is a forcedresonance frequency, or otherwise referred to as a frequency that is notequal to the resonant frequency of the enclosure, and f_(n) is thenatural resonant frequency of the enclosure, showing the establishmentof a robust field of coupled power in the enclosure at the f_(f)frequency;

FIG. 9 shows an enclosure with two probes each with a connector forinjecting EM energy into the enclosure, one probe being a TM probe andthe other being a TE probe;

FIG. 10 shows a probe, a connector, and an attenuator that is used toimprove the impedance match between the probe and the enclosure;

FIG. 11 shows a probe, a connector, and a passive matching circuit thatis used to improve the impedance match between the probe and enclosure;

FIG. 12 shows an active matching circuit connected between a probelocated in an enclosure and a transceiver, the active matching circuitcomprising a tunable capacitor, a dual-directional coupler, multiplepower sensors, and a comparator used to provide a closed-loop, variablematching circuit to improve the impedance match between the probe andthe enclosure;

FIG. 13 provides a side cross-sectional view of the cabinet of FIG. 2 atthe location of a drawer with the drawer removed for clarity, showingthe placement of two probe antennae in a “ceiling mount” configurationfor establishing a robust EM field in the drawer when it is in place inthe cabinet in the closed position;

FIG. 14 is a perspective view of the metallic enclosure showing theprobe configuration of FIG. 13 again showing the two probe antennae forestablishing a robust EM field in a drawer to be inserted;

FIG. 15 is a cutaway perspective side view of the metallic enclosure orframe in which are mounted the dual probe antennae of FIGS. 13 and 14with the drawer removed for clarity;

FIG. 16 is a frontal perspective view of the view of FIG. 14 with acutaway plastic drawer in place in the metallic enclosure and furthershowing the dual ceiling mount probe antennae protected by anelectromagnetically inert protective cover, and further showing coolingsystem components mounted at the back of the cabinet near the drawer'sback, the drawing also showing a partial view of a drawer slidemechanism for ease in sliding the drawer between open and closedpositions in the cabinet, the drawer front and rear panels having beencutaway in this view;

FIG. 17 is a frontal perspective view at the opposite angle from that ofFIG. 16 with the plastic drawer completely removed showing the dualceiling mount probe antennae protected by the EM inert protective covermounted to the metallic enclosure, and further showing the coolingsystem components of FIG. 16 mounted at the back of the cabinet as aspring loading feature to automatically push the drawer to the openposition when the drawer's latch is released, the figure also showing amounting rail for receiving the slide of the drawer;

FIG. 18 is a schematic view with measurements in inches of the placementof two TE₀₁ mode probes in the top surface of the enclosure shown inFIGS. 13-15;

FIG. 19 is a schematic view of the size and placement within the drawerof FIG. 16 of two microstrip or “patch” antennae and their microstripconductors disposed between respective antennae and the back of thedrawer at which they will be connected to SMA connectors in oneembodiment, for interconnection with other components;

FIG. 20 is diagram of field strength in an embodiment of an enclosurewith a probe placed in the enclosure at a position in accordance withthe diagram of FIG. 19;

FIG. 21 is a lower scale drawing of the field intensity diagram of FIG.20 showing a clearer view of the field intensity nearer the front andback walls of the enclosure; and

FIGS. 22A and 22B together present a block electrical and signal diagramfor a multiple-drawer medical cabinet, such as that shown in FIG. 2,showing the individual multiplexer switches, the single RFID scanner,and power control.

FIG. 23 is a front perspective view of a mobile dispensing cart having aplurality of lockable drawers, each of which may be assigned to aparticular patient and contain medical articles to be dispensed to thatpatient;

FIG. 24 is a top perspective view of a drawer from the cart of FIG. 23showing pockets in the drawer for organizing and separating variousmedical articles to be dispensed to the patient to whom the drawer hasbeen assigned;

FIG. 25 is a block diagram of a management system for a mobile cartincluding a computer system, local memory, remote server and remote databases, the mobile cart having Faraday cages enclosing multiple drawersfor reading RFID devices on articles stored in drawers;

FIG. 26 is a side perspective view of a Faraday cage enclosure fortaking the inventory of wireless devices contained in a mobiledispensing cart;

FIG. 27 is a block diagram flow chart of the creation of a medicalarticle data base and a patient data base for a mobile cart;

FIG. 28 is a schematic block diagram of a computer program that providesa method for managing access to and inventory of a mobile dispensingcart in which articles removed from the cart are checked against a database for a patient and if the article removed was not stored in the cartfor the particular patient, an alarm is given;

FIG. 29 is a flow chart of managing access to a mobile cart andmonitoring the removal of articles from the cart to assure that they areremoved for the correct patient; and

FIG. 30 is a screen shot of a program by which the expiration dates ofmedical articles in a mobile dispensing cart can be checked.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now in more detail to the exemplary drawings for purposes ofillustrating embodiments of the invention, wherein like referencenumerals designate corresponding or like elements among the severalviews, there is shown in FIG. 1 a schematic representation of a partialenclosure 20 in which a plurality of medical articles 22 are stored,each with a respective RFID tag 24 that has a unique identificationnumber. The partial enclosure may comprise a drawer having a front 26, aleft side 28, a right side 30, a rear 32, and a bottom 34. Thesearticles are randomly distributed in the drawer with the RFID tagsfacing in various and random directions.

As used in regard to the embodiments herein, “reader” and “interrogator”refer to a device that may read or write/read. The data capture deviceis always referred to as a reader or an interrogator regardless ofwhether it can only read or is also capable of writing. A readertypically contains a radio frequency module (a transmitter and areceiver, sometimes referred to as a “transceiver”), a control unit, anda coupling element (such as an antenna or antennae) to the RFID tag.Additionally, many readers include an interface for forwarding dataelsewhere, such as an RS-232 interface. The reader, when transmitting,has an interrogation zone within which an RFID tag will be activated.When within the interrogation zone, the RFID tag will draw its powerfrom the electrical/magnetic field created in the interrogation zone bythe reader. In a sequential RFID system (SEQ), the interrogation fieldis switched off at regular intervals. The RFID tag is programmed torecognize these “off” gaps and they are used by the tag to send data,such as the tag's unique identification number. In some systems, thetag's data record contains a unique serial number that is incorporatedwhen the tag is manufactured and which cannot be changed. This numbermay be associated in a data base with a particular article when the tagis attached to that article. Thus, determining the location of the tagwill then result in determining the location of the article to which itis attached. In other systems, the RFID tag may contain more informationabout the article to which it is attached, such as the name oridentification of the article, its expiration date, its dose, thepatient name, and other information. The RFID tag may also be writableso that it can be updated.

As used in regard to the embodiments herein, “tag” is meant to refer toan RFID transponder. Such tags typically have a coupling element, suchas an antenna, and an electronic microchip. The microchip includes datastorage, also referred to as memory.

FIG. 2 presents a representative medical dispensing cabinet 40comprising a plurality of movable drawers 42. In this embodiment, thereare five drawers that slide outwardly from the cabinet so that access isprovided to the contents of the drawers. FIG. 1 is a schematic diagramof a representative drawer that may be positioned within the cabinet ofFIG. 2 for sliding outward to provide access to the drawer's contentsand for sliding inward into the cabinet to secure the drawer's contents.The cabinet also comprises an integral computer 44 that may be used tocontrol access to the drawers and to generate data concerning access andcontents, and to communicate with other systems. In this embodiment, thecomputer generates data concerning the number and type of articles inthe drawers, the names of the patients for whom they have beenprescribed, the prescribed medications and their prescribedadministration dates and times, as well as other information. In asimpler system, the computer may simply receive unique identificationnumbers from stored articles and pass those identification numbers to aninventory control computer that has access to a data base for matchingthe identification numbers to article descriptions.

Such a cabinet may be located at a nursing station on a particular floorof a health care institution and may contain the prescriptions for thepatients of that floor. As prescriptions are prepared for the patientsof that floor, they are delivered and placed into the cabinet 40. Theyare logged into the integral computer 44, which may notify the pharmacyof their receipt. A drawer may also contain non-prescription medicalsupplies or articles for dispensing to the patients as determined by thenursing staff. At the appropriate time, a nurse would access the drawerin which the medical articles are stored through the use of the computer44, remove a particular patient's prescriptions and any needednon-prescription articles, and then close the drawer so that it issecured. In order to access the cabinet, the nurse may need to providevarious information and may need a secure access code. The drawers 42may be locked or unlocked, as conditions require.

The computer 44 in some cases may be in communication with otherfacilities of the institution. For example, the computer 44 may notifythe pharmacy of the health care institution that a patient'sprescription has been removed from the cabinet for administration at aparticular day and time. The computer may also notify the financedepartment of the health care institution of the removal ofprescriptions and other medical articles for administration to aparticular patient. This medication may then be applied to the patient'saccount. Further, the computer 44 may communicate to administration forthe purpose of updating a patient's Medication Administration Record(MAR), or e-MAR. The medication cabinet 40 computer 44 may be wirelesslyconnected to other computers of the health care institution or may havea wired connection. The cabinet may be mounted on wheels and may bemoved about as needed or may be stationary and unable to move.

Systems that use RFID tags often employ an RFID reader in communicationwith one or more host computing systems that act as depositories tostore, process, and share data collected by the RFID reader. Turning nowto FIGS. 3 and 4, a system and method 50 for tracking articles are shownin which a drawer 20 of the cabinet 40 of FIG. 2 is monitored to obtaindata from RFID tags disposed with articles in that drawer. As mentionedabove, a robust field of EM energy needs to be established in thestorage site so that the RFID tags mounted to the various storedarticles will be activated, regardless of their orientation.

In FIGS. 3 and 4, the tracking system 50 is shown for identifyingarticles in an enclosure and comprises a transmitter 52 of EM energy aspart of an RFID reader. The transmitter 52 has a particular frequency,such as 915 MHz, for transmitting EM energy into a drawer 20 by means ofa transmitting antenna 54. The transmitter 52 is configured to transmitthe necessary RFID EM energy and any necessary timing pulses and datainto the enclosure 20 in which the RFID tags are disposed. In this case,the enclosure is a drawer 20. The computer 44 of an RFID reader 51controls the EM transmitter 52 to cycle between a transmit period and anon-transmit, or off, period. During the transmit period, thetransmitted EM energy at or above a threshold intensity level surroundsthe RFID tags in the drawer thereby activating them. The transmitter 52is then switched to the off period during which the RFID tags respondwith their respective stored data.

The embodiment of FIG. 3 comprises a single transmitting probe antenna54 and a single receiving antenna 56 oriented in such a manner so as tooptimally read the data transmitted by the activated RFID tags locatedinside the drawer 20. The single receiving antenna 56 is communicativelycoupled to the computer 44 of the reader 50 located on the outside ofthe drawer 20 or on the inner bottom of the drawer. Other mountinglocations are possible. Coaxial cables 58 or other suitable signal linkscan be used to couple the receiving antenna 56 to the computer 44. Awireless link may be used in a different embodiment. Although not shownin the figures, those skilled in the art will recognize that variousadditional circuits and devices are used to separate the digital datafrom the RF energy, for use by the computer. Such circuits and deviceshave not been shown in FIGS. 3 and 4 to avoid unneeded complexity in thedrawing.

The embodiment of FIG. 4 is similar to the embodiment of FIG. 3 butinstead uses two transmitting probe antennae 60 and 62 and threereceiving antennae 64, 66, and 68. The configuration and the number oftransmitting probe antennae and receiving antennae to be used for asystem may vary based at least in part on the size of the enclosure 20,the frequency of operation, the relationship between the operationfrequency and the natural resonance frequency of the enclosure, and theexpected number of RFID tags to be placed in it, so that all of the RFIDtags inside the enclosure can be reliably activated and read. Thelocation and number of RFID reader components can be dependent on theparticular application. For example, fewer components may be requiredfor enclosures having a relatively small size, while additionalcomponents, such as shown in FIG. 4, may be needed for largerenclosures. Although shown in block form in FIGS. 3 and 4, it should berecognized that each receiving antenna 56, 64, 66, and 68 of the system50 may comprise a sub-array in a different embodiment.

The transmit antennae (54, 60, and 62) and the receive antennae (56, 64,66, and 68) may take different forms. In one embodiment as is discussedin more detail below, a plurality of “patch” or microstrip antennae wereused as the reader receiving antennae and were located at positionsadjacent various portions of the bottom of the drawer while the transmitantennae were wire probes located at positions adjacent portions of thetop of the drawer. It should be noted that in the embodiments of FIGS. 3and 4, the RFID reader 50 may be permanently mounted in the same cabinetat a strategic position in relation to the drawer 20.

One solution for reliably interrogating densely packed or randomlyoriented RFID tags in an enclosure is to treat the enclosure as aresonant cavity. Establishing a resonance within the cavity enclosurecan result in a robust electromagnetic field capable of activating allRFID tags in the enclosure. This can be performed by building anenclosure out of electrically conductive walls and exciting the metallicenclosure, or cavity, using a probe or probes to excite transverseelectric (TE) or transverse magnetic (TM) fields in the cavity at thenatural frequency of resonance of the cavity. This technique will workif the cavity dimensions can be specifically chosen to set up theresonance at the frequency of operation or if the frequency of operationcan be chosen for the specific enclosure size. Since there are limitedfrequency bands available for use in RFID applications, varying the RFIDfrequency is not an option for many applications. Conversely, requiringa specific set of physical dimensions for the enclosure so that thenatural resonant frequency of the enclosure will equal the availableRFID tag activating frequency will restrict the use of this techniquefor applications where the enclosure needs to be of a specific size.This latter approach is not practical in view of the many differentsizes, shapes, and quantities of medical articles that must be stored.

Referring now to FIG. 5, a rectangular enclosure 80 is provided that maybe formed as part of a medical cabinet, such as the cabinet shown inFIG. 2. It may be embodied as a frame disposed about a non-metallicdrawer in such a cabinet. The enclosure 80 is formed of metallic ormetallized walls 82, floor 83, and ceiling 84 surfaces, all of which areelectrically conductive. All of the walls 82, floor 83, and ceiling 84may also be referred to herein as “walls” of the enclosure. FIG. 5 alsoshows the use of an energy coupling or probe 86 located at the topsurface 84 of the enclosure 80. In this embodiment, the probe takes theform of a capacitor probe 88 in that the probe 88 has a first portion 94that proceeds axially through a hole 90 in the ceiling 84 of theenclosure. The purpose of the coupling is to efficiently transfer theenergy from the source 52 (see FIGS. 3 and 4) to the interior 96 of theenclosure 80. The size and the position of the probe are selected foreffective coupling and the probe is placed in a region of maximum fieldintensity. In FIG. 5, a TEN mode is established through the use ofcapacitive coupling. The length and distance of the bent portion 94 ofthe probe 88 affects the potential difference between the probe and theenclosure 80.

Similarly, FIG. 6 presents an inductive coupling 110 of the externalenergy to an enclosure 112. The coupling takes the form of a loop probe114 mounted through a side wall 116 of the enclosure. The purpose ofthis probe is to establish a TMoi mode in the enclosure.

The rectangular enclosures 80 and 112 shown in FIGS. 5 and 6 each have anatural frequency of resonance f_(n), shown in FIG. 7 and indicated onthe abscissa axis 118 of the graph by f_(n). This is the frequency atwhich the coupled power in the enclosure is the highest, as shown on theordinate axis 119 of the graph. If the injected energy to the enclosuredoes not match the f_(n) frequency, the coupled power will not benefitfrom the resonance phenomenon of the enclosure. In cases where thefrequency of operation cannot be changed, and is other than f_(n), andthe size of the enclosure cannot be changed to obtain an f_(n) that isequal to the operating frequency, another power coupling apparatus andmethod must be used. In accordance with aspects of the invention, anapparatus and method are provided to result in a forced resonance f_(f)within the enclosure to obtain a standing wave within the enclosure withconstructive interference. Such a standing wave will establish a robustenergy field within the enclosure strong enough to activate all RFIDtags residing therein.

When an EM wave that is resonant with the enclosure enters, it bouncesback and forth within the enclosure with low loss. As more wave energyenters the enclosure, it combines with and reinforces the standing wave,increasing its intensity (constructive interference). Resonation occursat a specific frequency because the dimensions of the cavity are anintegral multiple of the wavelength at the resonance frequency. In thepresent case where the injected energy is not at the natural resonancefrequency f_(n) of the enclosure, a solution in accordance with aspectsof the invention is to set up a “forced resonance” in an enclosure. Thisforced resonance is different from the natural resonance of theenclosure in that the physical dimensions of the enclosure are not equalto an integral multiple of the wavelength of the excitation energy, asis the case with a resonant cavity. A forced resonance can be achievedby determining a probe position, along with the probe length to allowfor energy to be injected into the cavity such that constructiveinterference results and a standing wave is established. The energyinjected into the enclosure in this case will set up an oscillatoryfield region within the cavity, but will be different from a standingwave that would be present at the natural resonance frequency f_(n) of aresonant cavity. The EM field excited from this forced resonance will bedifferent than the field structure found at the natural resonance of aresonant cavity, but with proper probe placement of a probe, a robust EMfield can nevertheless be established in an enclosure for RFID taginterrogation. Such is shown in FIG. 8 where it will be noted that thecurve for the forced resonance f_(f) coupled power is close to that ofthe natural resonance f_(n).

Turning now to FIG. 9, an enclosure 120 having two energy injectionprobes is provided. The first probe 86 is capacitively coupled to theenclosure 120 in accordance with FIG. 5 to establish a TE₀₁ mode. Thesecond probe 114 is inductively coupled to the enclosure 120 inaccordance with FIG. 6 to establish a TM₀₁ mode. These two probes areboth coupled to the enclosure to inject energy at a frequency f_(f) thatis other than the natural resonance frequency f_(n) of the enclosure.The placement of these probes in relation to the ceiling 126 and walls128 of the enclosure will result in a forced resonance within theenclosure 120 that optimally couples the energy to the enclosure andestablishes a robust EM field within the enclosure for reading RFID tagsthat may be located therein. The placement of these probes in relationto the walls of the enclosure, in accordance with aspects of theinvention, result in the forced resonance curve f_(f) shown in FIG. 8.

Referring briefly to FIG. 10, an impedance matching circuit 121 is shownthat functions to match the impedance of a source of energy 122 to theenclosure 120. The impedance matching circuit is located between thecoaxial cable 122 that feeds activating energy to the enclosure 120 andthe capacitively coupled probe 88 through a hole in the metallic ceiling126 of the enclosure. While the hole is not shown in the drawing of FIG.10, the insulator 123 that electrically insulates the probe from themetallic ceiling is shown. In this case, the matching circuit 121consists of only a resistive attenuator 124 used to reduce reflectionsof energy by the enclosure 120. However, as will be appreciated by thoseof skill in the art, capacitive and inductive components are likely toexist in the enclosure and in the coupling 88. FIG. 11 on the other handpresents an impedance matching circuit 124 having passive reactivecomponents for use in matching the impedance of the coaxial cable/energysource 122 and the enclosure 120. In this exemplary impedance matchingcircuit 124, an inductive component 125 and a capacitive component 127are connected in series, although other configurations, including theaddition of a resistive component and other connection configurationsare possible.

Passive components such as resistors, inductors, and capacitors shown inFIGS. 10 and 11 can be used to form matching circuits to match theimpedances of the energy source and the enclosure. This will aid incoupling power into the enclosure. However, the passive matching circuitwill improve the impedance match for a specific enclosure loading, suchas an empty enclosure, partially loaded, or fully loaded enclosure. Butas the enclosure contents are varied, the impedance match may not beoptimized due to the variation in contents in the enclosure causing theimpedance properties of the enclosure to change.

This non-optimal impedance match caused by variation in enclosureloading can be overcome by the use of an active impedance matchingcircuit which utilizes a closed loop sensing circuit to monitor forwardand reflected power. Referring now to FIG. 12, an active matchingcircuit 130 is provided that comprises one or several fixed valuepassive components such as inductors 132, capacitors 134, or resistors(not shown). In addition, one or several variable reactance devices,such as a tunable capacitor 134, are incorporated into the circuit;these tunable devices making this an active impedance matching circuit.The tunable capacitor 134 can take the form of a varactor diode,switched capacitor assembly, MEMS capacitor, or BST (Barium StrontiumTitanate) capacitor. A control voltage is applied to the tunablecapacitor 134 and varied to vary the capacitance provide by the device.The tunable capacitor 134 provides the capability to actively change theimpedance match between the probe 140 and the enclosure 142.

To complete the active matching circuit, a dual directional coupler 144along with two power sensors 146 can be incorporated. The dualdirectional coupler 144 and the power sensors 146 provide the ability tosense forward and reflected power between the RFID transceiver 148 andthe active matching circuit 130 and enclosure 142. Continuous monitoringof the ratio of forward and reflected power by a comparator 150 providesa metric to use to adjust the tunable capacitor 134 to keep the probe140 impedance matched to the enclosure 142. An ability to continuouslymonitor and improve the impedance match as the contents of the enclosureare varied is provided with the active matching circuit 130.

Referring now to the side cross-sectional view of FIG. 13, twoceiling-mounted 160 probe antennae 162 and 164 are shown mounted withinan enclosure, which may also be referred to herein as a cavity 166,which in this embodiment, operates as a Faraday cage. As shown, theFaraday cage 166 comprises walls (one of which is shown) 168, a back170, a floor 172, a ceiling 160, and a front 161 (only the position ofthe front wall is shown). All surfaces forming the cavity areelectrically conductive, are electrically connected with one another,and are structurally formed to be able to conduct the frequency ofenergy f_(f) injected by the two probes 162 and 164. In this embodiment,the cavity 166 is constructed as a metal frame 167 that may form a partof a medical supply cabinet similar to that shown in FIG. 2. Into thatmetal frame may be mounted a slidable drawer. The slidable drawer inthis embodiment is formed of electrically inert material, that is, it isnot electrically conductive, except for the front. When the drawer isslid into the cabinet to a closed configuration, the electricallyconductive front panel of the drawer comes into electrical contact withanother part or parts of the metallic frame 167 thereby forming thefront wall 161 of the Faraday cage 167.

The amount of penetration or retention into the cavity by the centralconductor 180 of each probe is selected so as to achieve optimumcoupling. The length of the bent portion 94 of the probe is selected toresult in better impedance matching. The position of the probe inrelation to the walls of the cavity is selected to create a standingwave in the cavity. In this embodiment, the probe antennae 162 and 164have been located at a particular distance D1 and D3 from respectivefront 161 and back 170 walls. These probe antennae, in accordance withone aspect of the invention, are only activated sequentially after theother probe has become inactivated. It has been found that thisconfiguration results in a standing wave where the injected energy wavesare in phase so that constructive interference results.

FIG. 14 is a front perspective view of the probe configuration of FIG.13 again showing the two probe antennae 162 and 164 located in aFaraday-type enclosure 166 for establishing a robust EM field in anarticle storage drawer to be inserted. It should be noted again that theFaraday cavity 166 is constructed as a metallic frame 167. In thisfigure, the cavity is incomplete in that the front surface of the “cage”is missing. In one embodiment, this front surface is provided by anelectrically conductive front panel of a slidable drawer. When thedrawer is slid into the cabinet, the front panel will make electricalcontact with the other portions of the metallic frame 167 therebycompleting the Faraday cage 166, although other portions of the drawerare plastic or are otherwise non-electrically conductive. In theembodiment discussed and shown herein, the two probe antennae 162 and164 are both located along a centerline between the side walls 166 and168 of the frame 166. The enclosure in one embodiment was 19.2 incheswide with the probe antennae spaced 9.6 inches from each side wall. Thiscentered location between the two side walls was for convenience in thecase of one embodiment. The probes may be placed elsewhere in anotherembodiment. In this embodiment, the spacing of the probes 162 and 164from each other is of little significance since they are sequentiallyactivated. Although not shown, two receiving antennae will also beplaced into the Faraday cage 166 to receive response signals from theactivated RFID tags residing within the cavity 166.

It will also be noted from reference to the figures that the probes eachhave a bent portion used for capacitive coupling with the ceiling 160 ofthe cavity, as is shown in FIG. 13. The front probe 162 is bent forwardwhile the back probe 164 is bent rearward A purpose for thisconfiguration was to obtain more spatial diversity and obtain bettercoverage by the EM field established in the drawer. Other arrangementsmay be possible to achieve a robust field within the cavity 166.Additionally two probes were used in the particular enclosure 166 sothat better EM field coverage of the enclosure 166 would result.

FIG. 15 is a cutaway perspective side view of the dual probe antennae162 and 164 of FIGS. 13 and 14, also with the drawer removed forclarity. The front probe 162 is spaced from the left side wall by ½λ ofthe operating frequency F_(f) as shown. It will be noted that the probeseach have a bent portion used for capacitive coupling with the ceiling160 of the enclosure 166 as shown in FIG. 13. The front probe 162 isbent forward for coupling with the more forward portion of the enclosurewhile the back probe 164 is bent rearward for coupling with the morerearward portion of the enclosure 166 to obtain more spatial diversityand obtain better coverage by the EM field in the drawer. Otherarrangements may be possible to achieve a robust field and furtherspatial diversity and coverage within the enclosure.

FIG. 16 is a frontal upward-looking perspective view of the frame 167forming a Faraday cage 166 showing a portion of a drawer 180 that hasbeen slidably mounted within the frame 167. The front metallic panel ofthe drawer has been removed so that its sliding operation can be moreclearly seen. It will also be noted that the dual ceiling mount probeantennae 162 and 164 have been covered and protected by anelectromagnetically inert protective cover 182. The drawer is formed ofa non-metallic material, such as a plastic or other electromagneticinert material having a low RF constant. The back 184 of the drawer hasalso been cut away so that a cooling system comprising coils 186 and afan 188 located in the back of the frame 167 can be seen. In this case,the drawer 180 is slidably mounted to the Faraday cage frame withmetallic sliding hardware 190. The sliding hardware of the drawer is sonear the side of the frame 167 of the enclosure 166 and may be inelectrical contact with the metallic slide hardware of the side walls168 of the enclosure that these metallic rails will have only a smalleffect on the EM field established within the enclosure.

FIG. 17 is an upward looking, frontal perspective view at the oppositeangle from that of FIG. 16; however, the drawer has been removed. Theframe 167 in this embodiment includes a mounting rail 192 for receivingthe slide of the drawer 180. In this embodiment, the mounting rail isformed of a metallic material; however, it is firmly attached to a side168 of the Faraday cage and thus is in electrical continuity with thecage. The figure also shows a spring mechanism 194 used to assist insliding the drawer outward so that access to the articles stored in thedrawer may be gained. The spring is configured to push automatically thedrawer outward when the drawer's latch is released.

FIG. 18 is a schematic view showing measurements of the placement of twoTE₀₁ mode capacitive coupling probes 162 and 164 in the ceiling 160 ofthe frame 167 shown in FIGS. 13-15. In this embodiment, the frequency ofoperation with the RFID tags is 915 MHz, which therefore has awavelength of 0.32764 meters or 1.07494 feet. One-half wavelength istherefore 0.16382 meters or 6.4495 inches. The length of the capacitivecoupling bent portion 200 of each of the probes is 5.08 cm or 2.00 in.The length of the axial extension 202 of the probes into the enclosureis 3.81 cm or 1.50 in., as measured from the insulator 204 into theenclosure 166. The probe configuration and placement in the embodimentwas based on an operation frequency of 915 MHz. In one embodiment, theenclosure 166 had a depth of 16.1 inches (40.89 cm), a width of 19.2inches (48.77 cm), and a height of 3 inches (7.62 cm). It was found thatthe optimum probe placements for this size and shape (rectangular)enclosure and for the 915 MHz operating frequency were: the front probewas spaced from the front wall by 5.0 inches (12.7 cm) and the rearprobe was spaced from the back wall by 5.0 inches (12.7 cm). As discussabove, the probes in this embodiment would only be activatedsequentially.

FIG. 19 is a schematic view of the size and placement within theenclosure 166 of FIG. 16 of two microstrip or “patch” antennae 210 and212 and their microstrip conductors 214 and 216 disposed between therespective antennae and the back of the enclosure at which they will beconnected to SMA connectors (not shown) in one embodiment. Feed lines 58(FIG. 3) may be connected to those SMA connectors and routed to thecomputer 44 for use in communicating the RFID signals for furtherprocessing. The measurements of the spacing of some of the microstripcomponents are provided in inches. The spacing of 9.7 in. is equivalentto 24.64 cm. The width of the microstrip line of 0.67 in. is equivalentto 17.0 mm. The spacing of 1.4 in. is equivalent to 3.56 cm. Otherconfigurations and types of receiving antennae may be used, as well asdifferent numbers of such antennae. In the present embodiment, thereceiving antennae are mounted on insulation at the bottom insidesurface of the metallic enclosure frame 167 so that the receiving patchantennae are not in contact with the metal surfaces of the Faraday cage.

Referring now to FIG. 20, the field intensity or field strength in theenclosure discussed above is shown with the ordinate axis shown involts/meter and the abscissa axis shown in meters. It will be seen fromthe diagram that the maximum field intensity occurs at about 5.0 inches(0.127 m) which results from the probe positioned at 5.0 inches (12.7cm) from the front wall and at a 915 MHz operating frequency. Referringnow to FIG. 21, the scale has been reduced although the large rise infield intensity can be seen at 5.0 inches. It can also be more clearlyseen that the field intensity falls off at the right wall but remainsstrong very close to the left wall. Therefore in an embodiment, a secondprobe was used that was placed 5.0 inches (12.7 cm) from the right wallthereby resulting in a mirror image field intensity to that shown inFIG. 21. The two probes 162 and 164 are activated sequentially and arenot both activated simultaneously. It will be noted that better EM fieldcoverage of the enclosure 166 is obtained with the two probes and thatRFID tags on articles positioned close to the front wall 161 will beactivated by the front probe 162 and that RFID tags on articlespositioned close to the rear wall 170 will be activated by the rearprobe 164 (see FIG. 13).

Although not intending to be bound by theory, in deriving the probelocation for TE modes in a square or rectangular non-resonant cavity,the following equation can be useful:

$N = {2 \times \frac{L_{2} - L_{1}}{\lambda_{g}}}$

where: N=positive non-zero integer, for example 1, 2, 3, etc.

-   -   L₁=distance between probe and back wall    -   L₂=distance between probe and front wall    -   λ_(g)=wavelength in the cavity

L₁ cannot be zero for TE modes, which implies that the probe for TE modeexcitation cannot be at the front or back wall. For TM modes, theequation is the same, but N can equal zero as well as other positiveintegers. The probe position cannot be λ_(g)/2 from the front or backwall. An L₁ and an L₂ are chosen such that N can be a positive integerthat satisfies the equation. For example, for the enclosure 166discussed above:L₁=4.785 inchesL₂=11.225 inchesλ_(g)=12.83 inchesTherefore,

$N = {{2 \times \frac{11.215 - 4.785}{12.83}} = 1.0}$

The actual enclosure had the probe located at a slightly differentlocation (5.0 inches) than that indicated by the equation (4.785 inches)which was possibly due to the insertion of a plastic drawer in thecavity, which introduces a change in the phase from the reflectedsignals. The equation above is set up such that the reflected phase fromboth front and back walls is equal, i.e., they are “in phase” at theprobe location.

The wavelength in the enclosure, λ_(g), can be calculated usingwaveguide equations. Equations for a rectangular cavity are shown below.The cutoff frequency is required for this calculation. The equationswill change for a cylindrical cavity or for other shapes.

The cutoff frequency is at the point where g vanishes. Therefore, thecutoff frequency in Hertz is:

$\left( f_{c} \right)_{mn} = {\frac{1}{2\pi\sqrt{\mu ɛ}}\sqrt{\left( \frac{m\;\pi}{a} \right)^{2} + \left( \frac{n\;\pi}{b} \right)^{2}}({Hz})}$

The cutoff wavelength in meters is:

$\left( \lambda_{c} \right)_{mn} = {\frac{2}{\sqrt{\left( \frac{m}{a} \right)^{2} + \left( \frac{n}{b} \right)^{2}}}(m)}$

where: a=inside width

-   -   b=inside height    -   m=number of ½-wavelength variations of fields in the “a”        direction    -   n=number of ½-wavelength variations of fields in the “b”        direction    -   ε=permittivity    -   μ=permeability

The mode with the lowest cutoff frequency is called the dominant mode.Since TE₁₀ mode is the minimum possible mode that gives nonzero fieldexpressions for rectangular waveguides, it is the dominant mode of arectangular waveguide with a>b and so the dominant frequency is:

$\left( f_{c} \right)_{10} = {\frac{1}{2a\sqrt{\mu ɛ}}({Hz})}$

The wave impedance is defined as the ratio of the transverse electricand magnetic fields. Therefore, impedance is:

$Z_{TE} = {\frac{E_{x}}{H_{y}} = {\frac{{jw}\;\mu}{\gamma} = {\left. \frac{{jw}\;\mu}{j\;\beta}\Rightarrow Z_{TE} \right. = \frac{k\;\eta}{\beta}}}}$

The guide wavelength is defined as the distance between two equal phaseplanes along the waveguide and it is equal to:

$\lambda_{g} = {{\frac{2\pi}{\beta} > \frac{2\pi}{k}} = \lambda}$${{{where}\mspace{14mu} k_{c}} = \sqrt{\left( \frac{m\;\pi}{a} \right)^{2} + \left( \frac{n\;\pi}{b} \right)^{2}}};{and}$$\beta = \sqrt{k^{2} - k_{c}^{2}}$

FIGS. 22A and 22B together provide a block electrical and signal diagramfor a multiple-drawer medical cabinet, such as that shown in FIG. 2. Inthis case, the cabinet has eight drawers 220, shown in both FIGS. 22Aand 22B. Each drawer includes two top antennae, two bottom antennae anda lock with a lock sensor 222 for securing the drawer. Signals to andfrom the antennae of each drawer are fed through an RF multiplexerswitch 224. Each RF multiplexer switch 224 in this embodiment handlesthe routing of RF signals for two drawers. RFID activation field andRFID received signals are fed through the respective RF multiplexerswitch 224 to a main RFID scanner 230 (see FIG. 22B). The scanner 230output is directed to a microprocessor 232 (see FIG. 22B) for use incommunicating relevant information to remote locations, in this case bywired connection 234 and wireless connection 236 (see FIG. 22B). Varioussupport systems are also shown on FIGS. 22A and 22B, such as powerconnections, power distribution, back up battery (see FIG. 22B),interconnection PCBA, USB support (see FIG. 22A), cooling (see FIG.22B), and others.

Turning now in more detail to FIG. 23, a mobile medication dispensingcart 300 is shown having a plurality of drawers 304, one or more ofwhich is for a particular patient being treated in the area near thecart. Multiple patients may have medications and other medical articlesstored in the cart. In this embodiment, the cart 300 also includes acomputer 310 with a display 312 and two input devices, one of which is astandard keyboard 314. In this case, the second input device is abiometric sensor/scanner 316 and is used to control access to thedrawers 304 of the cart 300. The biometric device reads fingerprints andthe computer 310 has, or is connected with a server 360 (discussed belowin relation to FIG. 25) that has, access to files that correlatefingerprints to personnel and access levels of those personnel. Thecomputer 310 or remote server determines if the health care provider(“HCP”) using the biometric scanner is in the data base as being allowedaccess to carts and is linked to any patient in the patient data basehaving a drawer 304 in this particular cart 300. If the HCP meets bothrequirements, he or she is allowed access to the drawers of the cart.Often mobile dispensing carts have locked drawers for security reasons.However, in a typical cart, the drawers are all locked and unlockedtogether. It is not possible to choose which to lock and which tounlock. Thus and HCP who gains access to one drawer has access to alldrawers and this is where the unfortunate activity of medication“shopping” arises. Such shopping can result in problems where the HCPtakes a medication from a drawer that is not the patient's for whom heor she is responsible and the HCP does not notice that the dosagediffers. Such shopping activity is curtailed due to aspects of theinvention shown herein in embodiments.

According to the particular program used, the HCP may be required toenter into the computer 310 by the keyboard 314 the patient name or codeto which the HCP is linked. If that patient has a drawer in the cart,the drawers will be unlocked for the HCP. The relevant drawer can thenbe opened by pulling its handle 306 and pulling it out of the cart. Ifthe HCP is not linked to any patient having a drawer in the cart, noaccess will be provided to the HCP. Other input devices may be used toperform the above, including a touch screen that operates both as adisplay (output device) and an input device.

Since these mobile dispensing carts 300 are typically not used foremergency medical articles, access to their drawers can be controlled sothat management and security of the contents of the cart are improved.Referring now to FIG. 24, the drawer 320 includes a locking feature 324at the back of the drawer to control access to the drawer. No furtherdetails of this locking feature are provided since those of skill in theart are aware of ways to provide a drawer locking system in a cart.However, mechanical and/or electrical controls over access to thedrawers can be implemented in such carts. Control over access may beprovided by the cart computer 310 or a remote server or other ways.

In accordance with the present embodiment, the mobile cart 300 of FIG.23 is provided with one or more RFID-enabled enclosures (not shown) inwhich one or more drawers are located. Embodiments of such RFIDenclosures can be seen in FIGS. 13-17. The RFID enclosures shown areconfigured as Faraday cages and each may contain an RFID exciter/reader.Both are controlled by the local computer 310 in this embodiment and areused to take an inventory of the drawers 304 within the enclosure. Asused herein, an RFID reader is a device that not only reads the serialnumber of a responding RFID tag, but also excites the tag to transmitthat serial number. Such RFID-enabled enclosures will enclose more thanone drawer and may enclose an entire row of drawers or multiple rows.Due to the size of the enclosure, it is unlikely that only singledrawers will be enclosed; however, if equipment should become less bulkyand costly, an arrangement where each drawer is separately enclosed maybe possible.

One or more drawers 304 of the cart 300 are allocated to a specificpatient and are stocked by the pharmacy for twenty-four hours of use,according to hospital practice. In one embodiment, each of themedications or supplies in a specific drawer within the cart isassociated with a specific patient via the identification numbers of theRFID tags that are attached to the medications or supplies in thedrawer. The pharmacy creates or builds a “patient data base” of themedical articles stocked in the cart for the particular patient and thatdata base is accessible from the cart. The RFID numbers of the medicalarticles are associated with that patient and stored in the data base;however, other arrangements for the data base link to the patient arepossible. Upon closing a drawer or drawers of the cart, the processor ofthe computer 310 will run an automated self-inventory of the cartthrough exciting and reading the RFID tags in the cart. At that time,processor can compare which medical articles remain in the cart andcompare them to the lists for the patients to determine if any aremissing. Referring to FIG. 24, three medical articles are shown in thepockets 322 of the drawer, each of which has an RFID tag 326 associatedwith it. In these three cases, the RFID tag is attached to the medicalarticle.

When an HCP identifies himself or herself to the local computer 310 andidentifies the patient, access to the drawers 304 of the cart 300 isgranted and medications or supplies can be withdrawn. Upon closing thedrawer (which will automatically cause it to lock in this embodiment),the local computer performs an automated self-inventory of theRFID-enabled enclosure in which all RFID tags in the cart are read andcompared against a data base inventory prior to the door being opened.The system then determines the difference between inventories beforethis person's access and after this person's access and updates theinventory data base. The medications and/or supplies taken from the cartare noted in the data base and may be scheduled for replacement. Thisapproach provides a higher level of inventory control, accountability,and prevents medication delivery errors.

FIG. 25 shows an embodiment of a mobile dispensing cart managementsystem 340 according to aspects of the invention. A cart 341 is shownwithin which are eleven slidable drawers 372 (all drawers are meant tobe indicated by numeral 372) in which are stored medical articles forparticular patients. The cart 341 also includes four RFID enclosures 342that comprise Faraday cages within which the multiple drawers arelocated when the drawers are in the closed configuration. The RFIDenclosures have electrically conductive walls and make electricalcontact with the front of the drawer which in this embodiment iselectrically conductive to provide a six-sided Faraday cage which actsby preventing (or significantly attenuating) electromagnetic energy fromentering or escaping the enclosure 342. Each Faraday cage is fitted withan RFID reader 344 configured to interrogate RFID tags located withinthe respective enclosure. Only one reader is shown in FIG. 25 in dashedlines due to the need to retain clarity in the drawing. The readers 344are connected to a computer 346 through a connection 348. The connection348 may be a wired connection, wireless connection, or any othersuitable connection for data transfer. In one embodiment, the physicalbody of the computing system 346 may be mounted to the cart 341,similarly as shown in FIG. 23.

The computing system 346 has a non-volatile memory 354 in which isstored at least one data base (“db”) such as the patient data basedescribed above, which may be a local database, or other. Thenon-volatile memory 354 comprises one or more computer readable mediawithin the computer system 346 and may be located within the computeritself or external to the computer. The memory is shown here as beingoutside the computer only for clarity of illustration in the discussionand is not meant to limit the invention in any way. In anotherembodiment, part or all of a relevant database may be stored on a server360 which may be remote from the cart and from the computer system 346.The computing system 346 connected to the remote server 360 has accessto a first remote data base 362 and a second remote data base 364, bothconnected to the server. As in the local computer, these remote databases may be stored on a memory that is internal to the server or thatis external to the server and may also include a patient data base or amedical article data base or other. Further, the server 360 may belocated nearby the local computer 346 or may be remote therefrom. Byremote, it is meant that it may be in the same room, or in the samewing, or in the same facility, or may be in the “cloud.” The connection366 to the server 360 may likewise be a wired connection, wirelessconnection, or any other suitable connection for data transfer. Thecomputer 346 also has a keyboard 336 as an input device and a display338 as an output device. The display could take the form of a touchscreen which would then provide both an input and an output device. Thecomputers shown herein can take different forms. They may be full sizedesktop computers, laptops, tablets, thin clients, or other.

In one embodiment, the data held on the local data base 352 (on localmemory 354) may depend on the location/specialty/facility using thecomputer system 346. In one embodiment, the remote database 362 at theserver 360 may serve as a main database and contain data and formularyfor all medical articles for all medicallocations/facilities/specialties. The local data base 352 may maintain acopy of the portion of data held on the remote data base 362 that ismost relevant to the computer system 346, but can access the remote database 362 when encountering medical items, medical containers, or otherinventory for different facilities/specialties/locations.

The enclosures 342 in FIG. 25 have openings at the front of the cart 341through which the drawers 372 may be slid into the cart. The drawers areplaced completely within the enclosures except for the front of thedrawers 374 (see FIG. 24) which in this embodiment close the respectiveopenings and complete the Faraday cage of the enclosure 342. The drawersinclude a number of medical items shown in FIG. 24 with each articlehaving an RFID tag 326 attached. As discussed previously, each RFID taghas a different stored identification number comprising a few bytes witha check digit. Manufacturers guarantee that each serial number is usedonly once. Some RFID tags have more complex codes for identifying theRFID tag. The RFID reader 344 will read those identification numbersfrom the tags, communicate them to the computer 346 which will comparethem against one or more data bases either locally 352 or remotelythrough a server 360 to identify the medical article to which the RFIDtag is attached. The process of using the identification numbers of thetags is discussed below.

In another aspect in accordance with the invention, in the case wherethe mobile medication cart does not include an RFID reader, the cart ismovable to a location at which an inventory enclosure is located. Thismay be on the same floor as patient rooms, in the pharmacy, orelsewhere, and is large enough that the entire cart may be pushed intothe enclosure. FIG. 26 presents an enclosure 390 of a much larger sizeso that it can accommodate the entire mobile dispensing cart 392. Inthis embodiment, enclosure 390 has a ceiling 394 and a floor 396 thatare electrically conductive. The enclosure 390 also has two fixed sidewalls 398 and 400 and a back (not shown) that are electricallyconductive. Part of an RFID reader system 402 is shown within theenclosure. The front part 404 of the enclosure is a hinged electricallyconductive door that, when closed, completes the Faraday cage of theenclosure 390. Instead of a door, the front 404 may be a flexible panelthat is also electrically conductive. Other approaches to providing acovering over the front opening are possible, provided that theycomplete the Faraday cage about the mobile dispensing cart 392 once itis moved completely within the enclosure 390. In an alternativeembodiment, all four sides of the enclosure may be made of flexiblepanels so that the enclosure can more easily be moved to anotherlocation. In one embodiment, the ceiling, floor, sides, back, and frontcan all be fitted with RFID readers/antennas 402 so that articles withinthe mobile dispensing cart having RFID tags can be accuratelyidentified.

The enclosure of FIG. 26 includes a ramp 406 that may or may not beattached to the floor 396 of the enclosure 390. The purpose of the rampis to facilitate rolling the mobile cart into the enclosure. Other meansare possible. The RFID exciter/reader 402 is located within theinventory enclosure to excite the RFID tags on the remaining medicationsand supplies in the mobile cart 392 and read those excited RFID tags. Ahost computer (not shown) associated with the inventory enclosure orelsewhere will determine the difference between the inventory ofremaining medications and supplies in the cart and the inventory takenprior to access given to the drawers. Upon completion of this excitationand reading process, the door 404 is opened and the mobile cartwithdrawn. The mobile cart may be resupplied with only the medicationsor supplies that were removed.

The inventory enclosure 390 may be formed in various ways. A metal framemay be used with flexible electrically conductive material forming thesides so that a door is not necessary. One wall of the flexibleelectrically-conductive material may be rolled up and the mobile cartpushed into the enclosure. The side may now be rolled down to resumeelectrical contact with three other sides to complete the Faraday cage.Other means of forming a Faraday cage may be used, including portablematerials that may be more easily moved from floor to floor or locationto location, assembled, operated, dissembled, and moved again.

It should be noted that use of a Faraday cage is highly beneficial inhealthcare facilities due to the ubiquitous presence of medical articlesthat have RFID tags. Without the ability to electrically isolate thedrawer or cart to be inventoried, an RFID reader may inadvertently readthe RFID tags of other pharmaceuticals on shelves outside the drawer orcart thereby giving the operator incorrect information that thoseexternal read articles are in the drawer or drawers of the cart.

FIG. 27 is a schematic diagram depicting an exemplary implementation ofan inventory management system 410 according to an embodiment of theinvention. Starting at the top, a data base of medical articles 420managed by the management system 410 is built. As an example, amedication vial 412 on which an RFID tag 414 is mounted is beingregistered with the system 410 by entering the RFID tag's serial number416 along with the relevant information 418 about the medication in thevial 412 into an “articles data base” 420 by the computer 422. In thiscase, the computer comprises a processor 424, a display 426, and aninput device 428 which in this case is a keyboard. An RFID reader 430obtains the RFID tag's serial number and assigns it to the medicationinformation regarding the medical article to which the RFID tag ismounted. In this case, the information about the medication comprises:the drug name, the dose, the volume, the expiration date, themanufacturer's name, the lot number, the NDC, and the UPC. Otherinformation may also be included. This is then stored in the ArticlesData Base or “Articles db” 420. Building the articles data base can bedone in different ways and may be automated or may be pre-prepared bythe medication manufacturer and given to the healthcare facility inelectronic form. The above is repeated for all medications and othermedical articles that may be placed in a mobile dispensing cart.

A drawer data base system is shown at the bottom of FIG. 27. In thisdiagram, the drawers 320 are stocked by the pharmacy patient by patientand the contents of the drawers are read into a patient data base whichthen links the identity of the patient to the cart and to certaindrawers and to the medical articles in the drawers of the cart. This isrepeated for all patients whose medical articles are in the cart. Theentry of medical article identifiers may be done by reading their RFIDtags or by other means.

Referring now to FIG. 28, a block diagram shows monitoring of the cartas access is obtained and medical articles are removed. The RFID reader344 is shown removed from the Faraday enclosures 342 and the drawers 372but this is for convenience of illustration only. In summary when adrawer or drawers 372 are closed, a program is run by the computer 464,the program stored in the computer's memory 470 or elsewhere, to managethe contents of the cart. Each of the enclosures 342 will read thecontents of the drawers in the enclosure and report the RFID serialnumbers received by the reader 344. The computer will compare those RFIDserial numbers to the patient data base 452 and note any articlesmissing. The computer stores such data for possible future reference.

Referring now to FIG. 29, a flow chart is provided that describes anembodiment of a method of managing the inventory of a mobile dispensingcart in accordance with aspects of the invention. The cart is stocked bythe pharmacy 480 with medical articles needed by patients in a certainarea of the facility for twenty-four hours. The cart is then moved 484to the area of the patients, which may be in the patients' room, in ahallway, or elsewhere. An HCP desires to take a medical article from thecart to dispense that article to a particular patient. The HCP obtainsaccess to the cart by identifying the HCP and the patient. The cart willthen unlock all drawers providing access to the medical articles storedin the cart.

The HCP removes a medical article 488 and closes the drawer 490. At thattime, the program that is managing and monitoring the cart inventoryscans all the drawers to determine if anything was taken and if so, whatwas taken 492. If the program determines that a medical article wastaken, it then compares that medical article to the data base of medicalarticles in the cart to determine if what was taken was a medicalarticle of the patient, for whom access to the cart was allowed. If theprogram does not find a match of the taken article to the patient's database, the program will provide an alarm 496. This alarm will mean thatthe HCP has taken a medical article stocked in the cabinet for adifferent patient. The alarm may be provided locally and may also becommunicated elsewhere as arranged. If the removal of the incorrectarticle was inadvertent, the alarm will prompt the HCP to return thearticle to the cart and search more carefully for the correct articlefor the patient.

Not only does this system manage the cart to avoid incorrect dispensing,it may also provide an HCP with a means to monitor the cart inventoryfor expired or recalled medical articles. The HCP may ask the cabinet toscan all medical articles for expiration dates. This may involvematching the RFID serial numbers to article information in the medicalarticle data base (FIG. 27, upper portion of figure) to obtain the exactexpiration date. The program would then ask the HCP what expirationperiod the HCP wants to search. A screen shot in FIG. 30 includes adrop-down list from which such expiration periods may be selected (forexample, 1 day, 10 days, etc.) A period is selected and the programcompares all expirations dates against that term. If any match, they arelisted in the section 504 below the drop-down box.

The program next proceeds to determining if any scanned medical articleshave been recalled by the manufacturer, or the FDA, or otherwise. Thecomparison of the identification of the detected medical articles in thetray are compared to a “Recalled” data base (not shown) and if anyarticles match recalled articles, it is then determined if a substitutemedical article exists. If none exists, an alarm is provided. If asubstitute article does exist, a substitute is located and may besupplied to the drawer. If no recalled articles exist in the drawer, theprogram indicates such status.

Multiple data bases may be employed in the system and method describedabove. According to one embodiment, the system 340 (FIG. 25) and themethod 489 (FIG. 29) may search one or more data bases of medicalarticle information matching the identification data. In one embodimentthe identification data may be found in multiple data bases each database containing different information. As by way of example and notlimitation, the name, dosage, lot code and expiration date may be on onedata base while recall status may be in another data base. In anotherembodiment all the medical item information may be held in one data basewhich may have its information on other data bases as backup. In yetanother embodiment, medical item information may be stored on a localdata base within the computing device connected to the enclosure, andthe local data base may be updated periodically over a networkconnection from one or more remote data bases.

Any alarms that are provided may be done so visually, such as bydisplayed on a computer screen, audibly, such as through speaker sounds,and/or tactile by vibrations. Other means or combinations of means forcommunicating an alarm condition may be used.

The invention will provide a means for more control over inventoryallocated to a specific patient. The invention will prevent “shopping”for medications to fulfill a patient's orders. The ability to includeFaraday cages and enclosures in which robust EM fields are produced whenthe enclosure is of a size much smaller than a resonant cavity for thefrequency of operation of the RFID devices results in a largeimprovement in the art. In one case, a 27 cubic feet enclosure is neededfor a resonant cavity at the frequency of operation. In accordance withaspects of the invention, a robust EM field similar to that of theresonant cavity was produced in a 1.4 cubic feet enclosure at the samefrequency thus resulting in a tremendous advantage in exciting andreading RFID tags in small enclosures.

According to one embodiment, the data files within the databasescontaining medical information may take the form of a comma separatedvalue list which may have multiple data fields and may look like “Name,Dosage, and Expiration.” Other serialized formats may be used to containthe data, including but not limited to, Extensible Markup Language(XML), JavaScript Object Notation (JSON), etc. The data may also takethe form of proprietary file formats created by medical articlemanufacturers. Furthermore, the data may contain a pointer or addressesto additional data providing additional information about the medicalitem or medical container. On example of additional information may be adata representation of a medical item's image. There are many differentfile or data formats that may be used to store medical information andany suitable format is contemplated within this invention. In oneembodiment, multiple datasets using different data formats containingmedical item information may be used, each for a particular medical itemmanufacturer or distributor. A system may be configured to identifyparticular datasets based on the identification data from a data carrier(such as an RFID tag). In an alternative embodiment, a single dataformat may be used across all medical items independent ofmanufacturers.

In one embodiment, an inventory management system and method inaccordance with the invention may use color indicators to communicateany differences/anomalies with the articles within the medical containerand the inventory list. The inventory management system and method mayalso provide expiration indicators. As an example, but not by way oflimitation, expiration indicators may include displaying a countdown ofthe number of days left until expiration of a medical article. Inanother embodiment, a color indicator using color gradients or colorcoding may indicate the life of the medical article such as green tored, white to black, etc. Each end of the color/gradient spectrum mayrepresent the life or expiration of a medical article.

Displays may use multiple windows. Each window may display differentinformation regarding the contents of the scanned medical container suchas a window for missing articles, a window for expired articles, awindow for incorrect or additional articles not part of the container'sinventory, a window for an inventory list, a window for recalledarticles, and a window for aggregated information. Each window may havean image display, name, dosage, number of articles, and expiration orrecall status indicator. Each window may also have a scroll bar foradditional data that does not fit in a single window. In an alternativeembodiment, a single window may be used and the user may be providedwith the ability to select what is displayed in the window.

The computers 310, 346, 422, and 464 across the figures may take anysuitable form, including but not limited to, an embedded computersystem, a system-on-chip (SOC), a single-board computer system (SBC)(such as, for example, a computer-on-module (COM) or system-on-module(SOM)), a laptop or notebook computer system, a smart phone, a personaldigital assistant (PDA), a server, a tablet computer system, a kiosk, aterminal, a mainframe, a mesh of computer systems, etc. The computersmay be a combination of multiple forms. The computers may include one ormore computer systems, be unitary or distributed, span multiplelocations, span multiple systems, or reside in a cloud (which mayinclude one or more cloud components in one or more networks).

In one embodiment, the computers may include one or more processors,memory, storage, an input/output (I/O) interface, a communicationinterface, and a bus. Although this disclosure describes and illustratesa particular computer system having a particular number of particularcomponents in a particular arrangement, this disclosure contemplatesother forms of computer systems having any suitable number of componentsin any suitable arrangement.

In one embodiment, a processor includes hardware for executinginstructions, such as those making up software. Herein, reference tosoftware may encompass one or more applications, byte code, one or morecomputer programs, one or more executable, one or more instructions,logic, machine code, one or more scripts, or source code, and viceversa, where appropriate. As an example and not by way of limitation, toexecute instructions, a processor may retrieve the instructions from aninternal register, an internal cache, memory or storage; decode anexecute them; and then write one or more results to an internalregister, an internal cache, memory, or storage. In one embodiment, aprocessor may include one or more internal caches for data,instructions, or addresses. Memory may be random access memory (RAM),static RAM, dynamic RAM or any other suitable memory. Storage maybe ahard drive, a floppy disk drive, flash memory, an optical disk, magnetictape, or any other form of storage device that can store data (includinginstructions for execution by a processor).

In one embodiment, storage may be mass storage for data or instructionswhich may include, but not limited to, a HDD, solid state drive, diskdrive, flash memory, optical disc (such as a DVD, CD, Blu-ray, and thelike), magneto optical disc, magnetic tape, or any other hardware devicewhich stores may store computer readable media, data and/or combinationsthereof. Storage may be internal or external to computer system.

In one embodiment, an input/output (I/O) interface includes hardware,software, or both for providing one or more interfaces for communicationbetween a computer system and one or more I/O devices. Computer systemsmay have one or more of these I/O devices, where appropriate. As anexample but not by way of limitation, an I/O device may include one ormore mouses, keyboards, keypads, cameras, microphones, monitors,display, printers, scanners, speakers, cameras, touch screens,trackball, trackpad, biometric input device or sensor, or the like.

In still another embodiment, a communication interface includeshardware, software, or both providing one or more interfaces forcommunication between one or more computer systems or one or morenetworks. A communication interface may include a network interfacecontroller (NIC) or a network adapter for communicating with an Ethernetor other wired-based network or a wireless NIC or wireless adapter forcommunications with a wireless network, such as a local wirelessnetwork. In one embodiment, a bus includes any hardware, software, orboth coupling components of a computer system to each other.

“Medical article” is used in this document its broadest sense. Forexample, a medical article can be a medical device, a pharmaceuticaldrug, a lab specimen, a blood product, a human organ, a hospital scrub,a surgical instrument, a medical implant, a sponge or gauze pad, ahealthcare institution code tray containing drugs to be tracked, and acode tray containing medical devices to be tracked.

As has been described, the various embodiments of the present inventionrelates to a system and method for medical article inventory andmanagement. For purposes of explanation, specific nomenclature is setforth to provide a thorough understanding of the present invention.Description of specific applications and methods are provided only asexamples. Various modifications to the embodiments will be readilyapparent to those skilled in the art and the general principles definedherein may be applied to other embodiments and applications withoutdeparting from the spirit and scope of the invention. Thus the presentinvention is not intended to be limited to the embodiments shown, but isto be accorded the widest scope consistent with the principles and stepsdisclosed herein.

Although RFID tags are used herein as an embodiment, other data carriersthat communicate through electromagnetic energy may also be usable.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments and elements, but, to the contrary, is intended tocover various modifications, combinations of features, equivalentarrangements, and equivalent elements included within the spirit andscope of the appended claims.

Unless the context requires otherwise, throughout the specification andclaims that follow, the word “comprise” and variations thereof, such as,“comprises” and “comprising” are to be construed in an open, inclusivesense, which is as “including, but not limited to.”

While particular embodiments of the present invention have beendescribed, it is understood that various different modifications withinthe scope and spirit of the invention are possible. The invention islimited only by the scope of the appended claims.

What is claimed is:
 1. An inventory management system for surroundingand electrically isolating a medical tray containing medical articles tobe tracked, each of the medical articles contained by the tray having anattached wireless data carrier that is responsive to electrical energyof a certain frequency range to transmit identification data that isindicative of the identity of the wireless data carrier, the inventorymanagement system comprising: an inventory enclosure comprisingassemblable and disassemblable walls, the sizes of the walls selected sothat when assembled, an interior space is created within the walls thatis large enough to receive a medical tray to be inventoried, the wallsbeing formed of electrically conductive material and electricallyinterconnected with other walls to electrically isolate a medical traylocated into the interior space, wherein the walls are configured toresult in the inventory enclosure being easily assembled, disassembled,moved, and reassembled in another location; wherein the walls of theinventory enclosure are configured to provide an opening to the interiorspace which allows for moving a medical tray into the interior space forinventorying and allows for the tray to be moved out of the interiorspace, and when the opening is closed, the plurality of wallselectrically isolate the tray located in the interior space; a datacarrier reader disposed within the interior space and configured totransmit interrogating electrical energy to data carriers located onmedical articles in a tray that is located within the interior space andto receive responsive identification data signals from data carriers,the reader also configured to communicate inventory data signalscontaining the data transmitted by the data carriers in the responsiveidentification data signals; a non-volatile memory in which is stored amedical article data base, the medical article data base comprisinginformation that links a data carrier to a medical article to which itis attached including identification of the medical article, thenon-volatile memory further comprising a tray inventory data base, thetray inventory data base including a list of medical articles assignedto be located in a tray; and a host computer having a communicationinterface that receives the inventory data signals from the reader, thehost computer being programmed to compare the received inventory datasignals to the medical article data base to determine information aboutmedical articles to which data carriers are attached in the tray that isbeing inventoried.
 2. The inventory management system of claim 1wherein: the non-volatile memory additionally stores a list of medicalarticles assigned to a tray; wherein the host computer is furtherprogrammed to compare the received inventory data signals from thereader, compare them to the stored tray inventory list, and indicatedifferences between the inventory indicated as actually being in thetray by the received inventory data signals and the stored inventorylist.
 3. The inventory management system of claim 1 wherein: the hostcomputer also being programmed to store a present inventory of a traythat is being inventoried within the inventory enclosure, compare thepresent inventory of the tray to a previous inventory of the same traythat is stored in the tray inventory data base, and indicate anydifference between the present inventory and the previous inventory. 4.The inventory management system of claim 1 wherein the walls of theenclosure comprise a floor, a ceiling, and a plurality of side walls,and wherein the side walls are flexible panels whereby the enclosure canbe more easily moved to another location.
 5. The inventory managementsystem of claim 1 wherein the inventory enclosure comprises flexibleelectrically conductive material forming the walls wherein at least oneof the flexible electrically-conductive material walls may be rolled upto admit a tray to the interior space for inventorying.
 6. The inventorymanagement system of claim 1 wherein one of the plurality of wallscomprises a floor panel and further comprising a ramp placed at thefloor panel to facilitate movement of the tray into and out of theinterior space of the enclosure.
 7. The inventory management system ofclaim 1: wherein the data carriers comprise radio frequencyidentification (RFID) tags; and wherein the walls comprise a ceiling, afloor, side walls, a back wall, and a front wall, all of which arefitted with an RFID reader; whereby the RFID tags on medical articleswithin the tray being inventoried in the interior space are more likelyto be accurately identified.
 8. The inventory management system of claim1 wherein the non-volatile memory comprises a data base of wireless datacarrier identifications linked to medical article data in which one ofthose medical article data is an expiration date of the respectivemedical article; wherein the host computer is further programmed toreceive the data carrier identification data, access the data base ofmedical article data corresponding to that data carrier identificationand compare the expiration date of the identified medical articles to aselected date; and wherein the host computer being further programmed toprovide a notice if the expiration date of a medical article falls on orbefore the selected date.
 9. The inventory management system of claim 1wherein the non-volatile memory includes a recalled data base in whichdata pertaining to recalled articles are stored; and wherein the hostcomputer further being programmed to compare the identification data ofthe medical articles in the tray to the recalled article data base inthe memory and if the comparison shows that a medical article isrecalled, to provide a notice of such recall status.
 10. The inventorymanagement system of claim 9 wherein the host computer is furtherprogrammed to access the recalled data base to determine if a substitutemedical article exists for any medical articles in the tray that haveshown to be recalled.
 11. The inventory management system of claim 10wherein the host computer is further programmed to provide an alarm ifno substitute medical article is found in the recalled medical data basefor any article shown to be recalled.
 12. The inventory managementsystem of claim 9 wherein the recalled data base is stored as a separatedata base on the non-volatile memory.
 13. The inventory managementsystem of claim 1 further comprising a visual display device; whereinthe non-volatile memory stores a medical article data base that includesdata concerning medical articles that are stored in the tray; andwherein the host computer is further programmed to: control the displaydevice to display a drop-down list of a plurality of selectable periodshaving varying time periods before an expiration date; receive aselection of one of the selectable periods before an expiration date;read the data carriers attached to the medical articles in the tray;access the non-volatile memory to locate an expiration date from themedical article data base for each of the medical articles located andread in the tray; compare expiration dates of the located and readmedical articles in the tray to the selected expiration period, andprovide a notice of the located articles' expiration within the selectedexpiration period if any of the located and read medical articles in thetray have expiration dates that fall in the selected expiration period.14. The inventory management system of claim 1 wherein the medicalarticles of the tray have been assigned to certain patients, the hostcomputer being further programmed to: create in a non-volatile memory astored medical articles data base of all medical articles in the trayand the names of the patients to whom the medical articles in the trayare to be administered; and compare a medical article determined to havebeen taken from the tray to the data base stored on the non-volatilememory of all medical articles in the mobile dispensing cart todetermine if the medical article taken was to be administered to thecorrect patient.
 15. A method of managing an inventory of a medical traycontaining medical articles to be tracked, each of the medical articlescontained by the tray having an attached wireless data carrier that isresponsive to electrical energy of a certain frequency range to transmitidentification data that is indicative of the identity of the wirelessdata carrier, the method of managing an inventory: surrounding andelectrically isolating a medical tray with an inventory enclosurecomprising assemblable and disassemblable walls, the sizes of the wallsselected so that when assembled, an interior space is created within thewalls that is large enough to receive a medical tray to be inventoried,the walls being formed of electrically conductive material andelectrically interconnected with other walls to electrically isolate amedical tray located into the interior space, wherein the walls areconfigured to result in the inventory enclosure being easily assembled,disassembled, moved, and reassembled in another location; wherein thewalls of the inventory enclosure are configured to provide an opening tothe interior space which allows for moving a medical tray into theinterior space for inventorying and allows for the tray to be moved outof the interior space, and when the opening is closed, the plurality ofwalls electrically isolate the tray located in the interior space;reading data carriers attached to medical articles contained in amedical tray that is disposed within the interior space by transmittinginterrogating electrical energy into the interior space and receivingresponsive identification data signals from data carriers; communicatingthe inventory data signals containing the data transmitted by the datacarriers in the responsive identification data signals; storing in anon-volatile memory a medical article data base, the medical articledata base comprising information that links a data carrier to a medicalarticle to which it is attached including identification of the medicalarticle, the non-volatile memory further comprising a tray inventorydata base, the tray inventory data base including a list of medicalarticles assigned to be located in a tray; and receiving the inventorydata signals by a communication interface of a host computer andcomparing the received inventory data signals to the medical articledata base to determine information about medical articles to which datacarriers are attached in the tray that is being inventoried.
 16. Themethod of managing an inventory of claim 15 comprising: storing a listof medical articles assigned to a tray in the non-volatile memory;comparing the received inventory data signals from the reader to thestored tray inventory list; and indicating differences between theinventory indicated as actually being in the tray by the receivedinventory data signals and the stored inventory list.
 17. The method ofmanaging an inventory of claim 15 comprising: storing a presentinventory of a tray that is being inventoried within the inventoryenclosure; comparing the present inventory of the tray to a previousinventory of the same tray that is stored in the tray inventory database, and indicating any difference between the present inventory andthe previous inventory.
 18. The method of managing an inventory of claim15 comprising rolling up flexible electrically conductive materialforming a wall of the inventory enclosure to admit a tray to theinterior space for inventorying.
 19. The method of managing an inventoryof claim 15, wherein the step of reading data carriers attached tomedical articles contained in a medical tray that is disposed within theinterior space comprises transmitting interrogating electrical energyinto the interior space and receiving responsive identification datasignals from data carriers by radio frequency identification (RFID) tagreaders located within the interior space.
 20. The method of managing aninventory of claim 15, further comprising: receiving the data carrieridentification data; comparing data carrier identification data to adata base of wireless data carrier identifications linked to medicalarticle data in which one of those medical article data is an expirationdate of the respective medical article; receiving access to a data baseof medical article data corresponding to that data carrieridentification and comparing the expiration date of the identifiedmedical articles to a selected date; and providing a notice if theexpiration date of a medical article falls on or before the selecteddate.
 21. The method of managing an inventory of claim 15, comprisingcomparing the identification data of the medical articles in the tray toa recalled article data base in the non-volatile memory and if thecomparison shows that a medical article is recalled, providing a noticeof such recall status.
 22. The method of managing an inventory of claim21, further comprising accessing the recalled data base to determine ifa substitute medical article exists for any medical articles in the traythat have shown to be recalled.
 23. The method of managing an inventoryof claim 22, further comprising providing an alarm if no substitutemedical article is found in the recalled medical data base for anyarticle shown to be recalled.
 24. The method of managing an inventory ofclaim 15, further comprising: storing a medical article data base thatincludes data concerning medical articles that are stored in the tray;controlling a display device to display a drop-down list of a pluralityof selectable periods having varying time periods before an expirationdate; receiving a selection of one of the selectable periods before anexpiration date; reading the data carriers attached to the medicalarticles in the tray; accessing the non-volatile memory to locate anexpiration date from the medical article data base for each of themedical articles located and read in the tray; comparing expirationdates of the located and read medical articles in the tray to theselected expiration period, and providing a notice of the locatedarticles' expiration within the selected expiration period if any of thelocated and read medical articles in the tray have expiration dates thatfall in the selected expiration period.
 25. The method of managing aninventory of claim 15, further comprising: storing in a non-volatilememory a medical articles data base of all medical articles in the trayand the names of the patients to whom the medical articles in the trayare to be administered; and comparing a medical article determined tohave been taken from the tray to the data base stored on thenon-volatile memory of all medical articles in the mobile dispensingcart to determine if the medical article taken was to be administered tothe correct patient.